Movements of shoulder blade

Movements of shoulder blade

Shoulder joint. Articulatio humeri

In the shoulder joint the shoulder-blade is connected to humerus. Joint pit is formed by cavitas glenoidalis scapulae, which is deepened by joining of labrum glenoidale to its margin. Caput humeri is the head. The joint capsule is strong and spacious, and it is attached to the margin of cavitas glenoidalis, on humerus on collum anatomicum (on the medial side it descends somewhat distally). The joint capsule is reinforced by several ligaments. Ligamenta glenohumeralia are being pulled from labrum glenoidale along the cavital side of the frontal wall of the joint capsule towards the humerus. Ligamentum coracohumerale descends from processus coracoideus scapulae on the anterior side of the joint capsule. The joint capsule is then reinforced by muscle tendons, which grows together with it. The muscle coverage is missing on the lower side, therefore the caput humeri is most often luxated in this direction. Tendon of long head biceps has a significant relation to the joint cavity and to the joint capsule. From its origin on tuberculum supraglenoidale scapulae runs through the joint cavity (it lays onto caput humeri), enters into sulcus intertubercularis humeri and abandons the joint. In the site of penetration through the joint capsule a synovial capsule is attached to it, which accompanied it as vagina synovialis intertubercularis into sulcus intertubercularis. In the surrounding of the joint there are many synovial burses (bursa subdeltoidea, bursa subcoracoidea, bursa subacromialis, bursa m. subscapularis subtendinea), which may connect with the joint cavity.

The shoulder joint is typical free spherical joint, with three axis of movement: ventral flexion (anteflexion) – dorsal flexion (dorsiflexion extension). Abduction (abduction) is possible only into the horizontal plane, further movement is restricted by fornix humeri, which tuberculum majus humeri leans onto (continuation of movement- raising arms upwards by abduction is possible only with simultaneous rotation of the shoulder-blade) – adduction (adduction ). Humeral pronation (rotation inwards) – humeral supination (outwardly rotation). Mentioned elementary pairs of movement can be combined.

The middle position of a joint – mild ventral flexion and abduction of about 45^o.

Note:

Elbow joint. Articulatio cubiti

In the elbow joint humerus, radius and ulna meet together. Individual bones meet together in such way that three independent parts are created – articulatio humeroradialis, articulatio humeroulnaris, articulatio radioulnaris proximalis. In articulatio humeroradialis, capitulum humeri is linked with fovea capitis radii, in articulatio humeroulnaris trochlea humeri is linked with incisura trochlearis ulnae, in articulatio radioulnaris proximalis circumferentia articularis radii is inserted in incisura radialis ulnae. Incisura radialis ulnae is completed with a circular ligament (ligamentum anulare radii), which both secures the position of capitulum radii, as well as its inner plane becomes an integral part of the joint pit. Joint capsule is attaching onto humerus proximally from fossa radialis, fossa coronoidea and fossa olecrani (these are located intraarticularly, at flexion and extension capitulum radii, processus coronoideus ulnae and olecranon ulnae are running into them). Along the sides, the attachment of the capsule is shifted somewhat distally; both epicondyles humeri are located extraarticularly. On ulna, the joint capsule is attached to the margins of incisura trochlearis, on radius it descends distally into the region of collum radii (here they create recessus sacciformis). The joint capsule is reinforced along the sides by collateral ligaments, which are fan-like running from both humeral epicondylus (ligamentum collaterale ulnare, ligamentum collaterale radiale).

Elbow joint is a composed joint. Its individual parts are differentiated from one another by their movement possibilities. Articulatio humeroradialis is a spherical joint with three axis of movement. However its mobility is limited by humeroulnar joint, which represents a one-axis joint (trochlear joint). Radioulnar proximal joint is a wheel-joint, with longitudinal axis of movement. By a combination of all three parts of the elbow joint, movements are possible alongside two axes. It is a flexion and an extension (in humeroradial and humeroulnar part) and rotational movements (supination and pronation) in humeroradial and proximal radioulnar part.

The middle position of a joint is in pronation and light flexion.

Radioulnar junctures. Juncturae radioulnares

Connection of radius with ulna are, apart from parts of elbow joint (articulatio radioulnaris proximalis), secured also by membrana interossea antebrachii and articulatio radioulnaris distalis.

Membrana interossea antebrachii is strengthened between the bodies of radius and ulna (margines interossei). In the proximal part there is a stronger fibrous band (chorda obliqua), which runs from tuberositas radii to processus coronoideus ulnae. Membrana interossea antebrachii links both antebrachial bones, restricts supination, and at the same time it also serves as a plane for adjoining of numerous antebrachial muscles.

Articulatio radioulnaris distalis. In this joint caput ulnae is connecting with incisura ulnaris radii (joint pit). The joint pit is completed by a plate of a fibrous cartilage (discus articularis), which attaches itself to the margin of incisura ulnaris radii and to processus styloideus ulnae. The joint capsule is attached to the margins of joint surfaces. It is peg joint (monoaxial), which enable rotational movements such as pronation and supination. Ulna is fixed during movement; distal end of radius is rotating around it. The movement in the joint is accompanied by concomitant movement in the elbow joint.

Hand joints. Articulationes manus

Hand joints consists articulatio radiocarpalis, articulatio mediocarpalis, articulatio ossis pisiformis, articulatio carpometacarpalis pollicis, articulationes carpometacarpales II.-V., articulationes metacarpophalangeales, articulationes interphalangeales manus.

Radiocarpal joint. Articulatio radiocarpalis

The joint pit is represented by facies articularis carpalis radii, extended ulnarly using discus articularis (from the distal radioulnar joint). Distal ulnar joint is therefore excluded from the contact with distal capal bones. Joint head is formed by os scaphoideum, os lunatum and os triquetrum. All three bones are joined together using ligamentua intercarpalia interossea. The joint capsule attaches itself on the margins of joint surfaces.

The joint creates a functional unit with joint that follows.

Mediocarpal joint. Articulatio mediocarpalis

In this joint proximal row of carpal bones (with exception of os pisiforme) are joined with distal row of bones. On radial side the head is created by os scaphoideum, joint pit is created by little planes on os trapezium, os trapezoideum and on ulnar side by os capitatum. On ulnar side is head formed by os capitatum and os hamatum, joint pit is formed by little planes on os scaphoideum, os lunatum and os triquetrum. Joint split therefore has a shape of a transversally positioned letter S.

Carpal bones are connected together using ligamenta intercarpea dorsalia, palmaria et interossea. An interosseal ligament is missing between os trapezium and os trapezoideum; joint split (cavity) of mediocarpal joint communicates through here with joint split (cavity) of articulationes metacarpophalangeales II. - V. Joint capsule is attached to the margins of joint surfaces, and it is reinforced by a row of ligaments. Ligamentum radiocarpeum palmare et dorsale runs from processus styloideus radii onto palmar and dorsal side of capal bones. Similar ligaments also run from processus styloideus ulnae (ligamentum ulnocarpeum palmare et dorsale). Os capitatum runs from palmar side into all directions to the adjoining carpal bones of ligamentum carpi radiatum. Ligamentum arcuatum carpi dorsale runs from the dorsal side of os scaphoideum onto the dorsal side os triquetrum. Similar variably occurring ligament is also on the palmar side (ligamentum arcuatum carpi palmare).

Both joints, articulatio radiocarpalis and articulatio mediocarpalis form a functional unit, which can be considered to be a joint of ellipsoidal type. For this reason movements along two axes are possible here. Palmar and dorsal hand flexion, and ulnar and radial hand duction (movement in way of ulnar fiction is more prominent). Combination of both types of movements results in circular movements (circumduction).

Articulatio ossis pisiformis

Os pisiforme with its joint surface is coming onto the joint surface of central side of os triquetrum. Joint capsule is attached onto the margins of joint surfaces. Ligamentum pisohamatum goes from os pisiforme to hamulus ossis hamati and to the basis of the 4th a 5th metacarpus ligamentum pisometacarpeum (mentioned ligaments represent basically the attachment tendon m. flexor carpi ulnaris, and os pisiforme is a sesamoideal ossicle in this tendon).

Sulcus et canalis carpi

Both rows of carpal bones, their processus and tuberosities, forms arch-shaped structure, which is dorsally inverted with its convexity. Tuberculum ossis scaphoidei and tuberculum ossis trapezii (eminentia carpi radialis) protrude into the palm on the radial side; another projection is on the ulnar side eminentia carpi ulnaris, which is formed by hamulus ossis hamati and os pisiforme. Concave sulcus on the palmar side (sulcus carpi) is bridged by a strong fibrous retinaculum – retinaculum flexorum, which connects both eminentiae carpi. That’s how canalis carpi is created, flexor tendons of hand and fingers and n. medianus pass through it into the palm.

Articulatio carpometacarpalis pollicis

In the joint the joint surfaces are joining on the basis of first metacarpus and on the basis of os trapezium, joint capsule is attached onto the margins of joint surfaces. This is a sellar-type of joint, and it enables movements along two axis. One of the pair of movement is abduction and adduction of a thumb (abduction and adduction of a thumb in relation to the 2nd finger), another pair of movement is the opposition and reposition of a thumb (during opposition the thumb is positioned against the remaining fingers). The capability of thumb opposition on a human hand enables grasping of tools.

Articulationes carpometacarpales II.-V.

In this composited joint the bases of 2nd to 5th metacarpus are meeting with distal row of carpal bones, contacts between joint surfaces on adverted metacarpal bases also belong here. The joint capsule is firm and it attaches to the margins of joint surfaces. The joint cavity communicates with mediocarpal joint, (through slit between os trapezium and os trapezoideum). The joint capsule is reinforced by an entire row of ligaments (ligamenta carpometacarpalia palmaria, dorsalia et interossea, ligamenta metacarpalia palmaria, dorsalia et interossea). The joint slit has irregular course, its mobility is minimal (amphiarthrosis).

Articulationes metacarpophalangeales

Metacarpal heads meet with the joint surfaces on the basis of proximal phalanges. On the palmar side there are joint pits deepened using fibrous plates – laminae fibrocartilagineae palmares. Joint capsules are attached on the margins of joint surfaces, and on the margin of lamina fibrocartilaginea. Frontal and dorsal part of the joint capsule is thinner and looser, along the sides the joint capsule is strong, and is furthermore reinforced using ligamentum collaterale ulnare et radiale.

The thumb joint is independent, heads of 2nd to 5th metacarpus are connected on the palmar side using the transversally oriented strong ligament, which grows together with lamina fibrocartilaginea (ligamentum metacarpeum transversum profundum). In lamina fibrocartilaginea palmaris of the thumb joint two sesamoideal bones are being constantly inserted (these bones are not an exception in other metacarpophalangeal joints).

According to the shape of joint surfaces, metacarpophalangeal joints belong to ellipsoidal joints, and possible movements inside them are flexion and extension, and abduction and adduction.

Articulationes interphalangeales manus

Adjoining phalanges are meeting using trochlear joints. Head is formed by trochlea phalangis, pit is formed by the basis of distally situated phalanx. Analogically, as with previous joints, the joint pits are on the palmar side arched using fibrous lamina fibrocartilaginea palmaris. The joint capsule is reinforced along the sides using ligamentum collaterale radiale et ulnare. Dorsal side of the joint capsule is reinforced by aponeurosis of the finger extensors.

The movements are trochlear-shaped, movements occurs as flexion and extension.

Bone junctions of lower extremity. Juncturae ossium extremitatis inferioris

Using junctions of girdle bones of lower extremities, a greater complex – pelvis (pelvis) is created. Pelvis is formed by both pelvis bones and caudal part of vertebral column (os sacrum and os coccygis).

Sacro-iliac joint. Articulatio sacroiliaca

Os coxae is attached to axial skeleton using this joint. Joint surfaces represent facies auricularis osiss coxae, and equally named joint surface on the sacral bone. Joint surfaces have an uneven surface, joint capsule is attached to the margins of joint areas, it is solid and short. Junction of both bones is secured by a row of very strong ligaments. Ligamenta sacroiliaca ventralia reinforce the joint capsule from the frontal side. Ligamenta sacroiliaca interossea are very strong, and they attach themselves onto tuberositas sacralis and tuberositas iliaca. Ligamenta sacroiliaca dorsalia run between spinae iliacae posteriores and tuberosities on the dorsal side of sacral bone. The joint is practical immobile (amphiarthrosis), due to uneven surface of its planes.

Other ligaments, which also partially participate on reinforcing of the pelvis are typically classified together with the above mentioned joint. Ligamentum iliolumbale links the dorsal part of crista iliaca with processus costarii L4 and L5. Ligamentum sacrospinale runs from spina ischiadica and attaches itself on the lateral margin of sacral bone and coccygis.

Ligamentum sacrotuberale runs in a similar way. It links tuber ischiadicum with lateral margin of os sacrum and os coccygis. From tuber ischiadicum, processus falciformis runs from this ligament frontally (it attaches itself to the lower margin of os coxae).

Ligamentum sacrospinale closes incisura ischiadica major by its positioning and course and changes it into foramen ischiadicum majus. This foramen is separated by the course of m. piriformis into two parts. The superior part (foramen suprapiriforme) serves for passing of n. et vasa glutea superiora, inferior part (foramen infrapiriforme) serves for passing of n. et vasa glutea inferiora, n. ischiadicus, n. cutaneus femoris posterior, vasa pudenda interna a n. pudendus.

Both ligaments transform incisura ischiadica minor into foramen ischiadicum minus, through which a tendon of m. obturatorius internus passes, and into fossa ischiorectalis n. pudendus and vasa pudenda interna.

Pubic symphysis. Symphysis pubica

In this unpaired synchrondrosis the frontal margins of pelvic bones are connected. Between facies symphysiales of both pubic bones, there is discus interpubicus (layer of fibrous cartilage, high at women about 45 mm, in men about 50 mm) inserted, inside which there is a sagitally oriented slit. Dorsal margin of discus overlaps the dorsal bone margins (eminentia retropubica), in women this formation is easily palpable per vaginam. The junction is reinforced by two strong ligaments.

Ligamentum pubicum superius is found on the cranial (upper) side of symphysis, stronger ligamentum arcuatum pubis fills the angle between lower margins of symphyses.

The junction is practically immobile. Towards the end of pregnancy, the symphysis somewhat softens due to the influence of hormones, and in labour enables slight enlargement of the birth canal.

Membrana obturatoria

Foramen obturatum is incompletely closed by a strong fibrous membrane (membrana obturatoria). Sulcus obturatorius is transformed into canalis obturatorius (for n. et vasa obturatoria) by the attachment of membrana obturatoria. Both planes (faces) of membrana obturatoria are sites of origin of mm. obturatorii.